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Question

Just like we can partially apply functions to get new functions, we can partially apply type parameters and get new type constructors from them.

How can a parameter be applied to something else? I think it should actually be

Just like we can partially apply functions to get new functions, we can partially apply type constructor (giving them less type parameters then they expect) and get new type constructors from them.

Do you agree?

This is a discussion-based question, a better fit for /r/haskell — , May 22 '20 at 21:37
@MichaelLitchard, can you explain the rational behind your statement? What does make this quesion opinion-based? — Enlico, May 22 '20 at 21:55
I disagree, because it is informally accepted to say eg. "apply the arguments to the function" and their usage is a valid extension of this. — moonGoose, May 22 '20 at 22:02

score 6 · Accepted Answer · answered May 22 '20 at 22:04

6

The author seems to use apply to mean both "the function to the parameters" as well as "the parameters to the function".

Further down we read

we'll partially apply Either by feeding it only one parameter

Where the meaning is the former, as well as

Let's apply the type parameter to Maybe and see what the kind of that type is.

ghci> :k Maybe Int

where the meaning is the latter.

answered May 22 '20 at 22:04

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From my non-native English perspective the former and the latter are both correct as much as `Int -> Char` and `Char -> Int` are the same type, hence the question. It seems that my non-English-ness fooled me, thus making the question opinion-based. – Enlico May 22 '20 at 23:10

Typo in Learn you a Haskell for Great Good?

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